Mileage and Cold Weather

It’s coming! I don’t like it, but there is nothing I can do about it. Winter is almost here. Cold, wind, snow, icy roads, white outs are all part of the Canadian winter. And of course, the weather has an effect on your mileage.

Battery condition will determine how (if?) your vehicle starts. Some people use a battery blanket to keep it warm. This wraps around the battery and plugs into your normal household socket.

Block heaters are considered a necessity. These are a small heating element installed in place of the frost plug in the engine block. They keep the antifreeze warm, and require from 450 watts to 750 watts of power. Many people put them on a timer set for about four hours.

When the engine is stated on a cold morning, the computer will increase the idle speed to about 1100 rpm to help warm up the engine. With modern engines, they can be driven gently very soon after starting. But that’s not the problem. You do need to see where you are going!

The inside of the windshield is often cold enough to freeze the moisture from your breath to the inner surface. To use the defroster, the engine has to be warm enough to remove the frost on the windshield. This normally requires idling, which cost you fuel.

There also may be frost on the outside of the windows. Plastic scrappers are used to remove this frost, usually while the car is warming up (idling). And of course, you will have to remove the snow from the vehicle.

If you have a garage, you can alleviate some of these problems. Even an unheated garage helps. Heated underground parking? Great! I had an insulated, heated garage, but rarely used the furnace. The heat from the engine would provide enough warmth to keep the entire garage at a reasonable temperature.

Now it’s time to join the traffic. In some ways the hypermilers have an advantage because they are already doing things that the rest of the drivers are forced into. Accelerating slowly helps to prevent spinning wheels on icy roads. Braking gently helps to keep your vehicle under control.

Switching to snow tires is a good idea for safety. All season radials become hard at about 7 degrees Celsius (44 degrees F). Traction for both accelerating and braking is reduced. However, snow tires have a greater rolling resistance, and will reduce your mileage. They also seem to wear faster if driven a lot on bare roads.

Another winter challenge is new snow. An inch of snow on the road will dramatically increase the power required to maintain a given speed. It can also hide icy patches, which can make both starting and stopping a problem.

There are more challenges to winter driving, but I believe that safe hypermilers will do well. So go placidly through the roads, be safe and enjoy yourself.

Ken Moore